Encode battery charge source in action states

[LordMike]

Summary

This PR changes battery action states so they encode charge source directly in the public contract instead of exposing a generic charge state plus a separate charge_source field.

It changes battery schedule/action outputs from:

• charge + charge_source=grid|pv|grid_pv

to:

• charge_grid
• charge_pv
• charge_grid_pv

hold and discharge remain unchanged.

What this changes

• Updates public battery action/state outputs across optimizer, projection, snapshot, and sensor surfaces
• Removes the emitted charge_source attribute/field from:
  • battery schedule points
  • coordinator snapshot / planner projection outputs
  • battery action sensor attributes
• Converts battery action sensors to enum sensors with explicit allowed options
• Updates compact plan_details battery action codes to preserve source information:
  • c_g
  • c_p
  • c_gp
  • d
  • h
• Changes mixed hourly rollups in projection.py to join multiple non-hold compact action codes with + to avoid ambiguous strings

Tests

Validated with targeted pytest runs:

• tests/optimizer/test_optimizer_scenarios.py
• tests/integration/test_integration_runtime.py
• tests/integration/test_integration_e2e.py

Result: 61 passed

Docs

Updates entity/service and optimizer API docs to reflect the new battery action contract and compact action encoding.

Notes

• Removes regression-style test wording focused on charge_source as a legacy field; tests assert the positive contract only
• Leaves internal optimizer helper naming such as _charge_source_permissions unchanged because it is not part of the public API